Systems and methods for delay management in distributed antenna system with direct digital interface to base station

ABSTRACT

A method for measuring downlink delay in a radio system includes applying a digital representation of a Gaussian pulse to a digital interface of the radio system; marking the digital representation of the Gaussian pulse with respect to a frame of digital data with a marker; propagating the Gaussian pulse in the radio system to an antenna, the radio system configured to convert the digital representation of the Gaussian pulse to a radio frequency signal transmitted at the antenna; measuring when the Gaussian pulse occurs in the radio frequency signal based on the marker; and determining a downlink propagation delay for the radio system between application of the digital representation of the Gaussian pulse at the digital interface and transmission of the radio frequency signal at the antenna.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/506,370 filed Oct. 3, 2014 and entitled “SYSTEMS AND METHODS FORDELAY MANAGEMENT IN DISTRIBUTED ANTENNA SYSTEM WITH DIRECT DIGITALINTERFACE TO BASE STATION”, which claims the benefit of U.S. ProvisionalPatent Application Ser. No. 61/887,748 filed on Oct. 7, 2013 andentitled “SYSTEMS AND METHODS FOR DELAY MANAGEMENT IN DISTRIBUTEDANTENNA SYSTEM WITH DIRECT DIGITAL INTERFACE TO BASE STATION”, each ofwhich are hereby incorporated herein by reference.

BACKGROUND

Distributed Antenna Systems (DAS) are used to distribute wireless signalcoverage into buildings or other substantially closed environments. Theantennas are typically connected to a radio frequency (RF) signalsource, such as a service provider's base station. Various methods oftransporting the RF signal from the RF signal source to the antenna havebeen implemented in the art.

SUMMARY

A method for measuring downlink delay in a radio system includesapplying a digital representation of a Gaussian pulse to a digitalinterface of the radio system; marking the digital representation of theGaussian pulse with respect to a frame of digital data with a marker;propagating the Gaussian pulse in the radio system to an antenna, theradio system configured to convert the digital representation of theGaussian pulse to a radio frequency signal transmitted at the antenna;measuring when the Gaussian pulse occurs in the radio frequency signalbased on the marker; and determining a downlink propagation delay forthe radio system between application of the digital representation ofthe Gaussian pulse at the digital interface and transmission of theradio frequency signal at the antenna.

DRAWINGS

Understanding that the drawings depict only exemplary embodiments andare not therefore to be considered limiting in scope, the exemplaryembodiments will be described with additional specificity and detailthrough the use of the accompanying drawings, in which:

FIGS. 1A-1D are block diagrams of exemplary embodiments of systems formeasuring downlink and uplink delays in distributed antenna systems;

FIG. 2 is a block diagram of exemplary embodiments of a host unit usedin distributed antenna systems, such as the exemplary distributedantenna system in FIGS. 1A-1D;

FIG. 3 is a block diagram of an exemplary embodiment of an antenna unitused in distributed antenna systems, such as the exemplary distributedantenna system in FIGS. 1A-1D;

FIG. 4 is a flow diagram illustrating an exemplary embodiment of amethod for measuring downlink delay in a distributed antenna system; and

FIG. 5 is a flow diagram illustrating an exemplary embodiment of amethod for measuring uplink delay in a distributed antenna system.

FIGS. 6A-6B show a flow diagram illustrating an exemplary embodiment ofa method for measuring delay in a distributed antenna system.

In accordance with common practice, the various described features arenot drawn to scale but are drawn to emphasize specific features relevantto the exemplary embodiments. Like reference numbers and designations inthe various drawings indicate like elements.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings that form a part hereof, and in which is shown byway of illustration specific illustrative embodiments. However, it is tobe understood that other embodiments may be utilized and that logical,mechanical, and electrical changes may be made. Furthermore, the methodpresented in the drawing figures and the specification is not to beconstrued as limiting the order in which the individual steps may beperformed. The following detailed description is, therefore, not to betaken in a limiting sense.

The embodiments described below describe methodology and a system tomeasure delay between different domains, such as (1) a digital input toan analog radio frequency (RF) output; and (2) a radio frequency (RF)input to a digital output. More specifically, the embodiments describedbelow describe a distributed antenna system under test and componentswithin the distributed antenna system under test including at least onedigital host communicatively coupled to at least one antenna unit via acommunication medium. In exemplary embodiments, a digital interface ofthe digital host is at least one of a Common Public Radio Interface(CPRI) base station interface, an Open Base Station ArchitectureInitiative (OBSAI) base station interface, and an Open Radio Interface(ORI) base station interface. In exemplary embodiments, the antenna unitincludes an antenna. In exemplary embodiments, test equipment iscommunicatively coupled to both the digital interface and the antenna toaid in determining the downlink and uplink delay in the distributedantenna system under test.

In exemplary embodiments, the antenna unit is multi-standard and capableof receiving at least one signal and converting it to radio frequency(RF) and transmitting it using at least one antenna. In exemplaryembodiments, the antenna unit is not specific to a number of channels oran air protocol and does not necessarily require any hardware changewhen channels are added or removed, or a new modulation type or airprotocol is used. In exemplary embodiments, a plurality of signalinterface units convert a plurality of external device signals receivedfrom a plurality of external devices and representing individualchannels into a single radio system signal that is transported throughthe distributed switching network to at least one antenna unit thatconverts the single radio system signal into radio frequency (RF)signals and transmits them using at least one antenna. In exemplaryembodiments, the at least one antenna unit includes a singledigital/analog convertor and a single RF converter that can up-convertthe entire radio system signal into RF spectrum having various channels.

In exemplary embodiments, the digital host is configured to communicatechannelized signals with an external device. As described herein,channelized signals are specific to a particular channel. In exemplaryembodiments, the channelized signals are baseband data, such aschannelized in-phase (I) and quadrature (Q) data in UQ pairs. Thechannelized signals are not positioned relative to one another andrequire additional baseband conversion before RF conversion andtransmission can be performed. Specifically, if a system communicatedthe channelized signals to an antenna unit, additional processing wouldbe required at the antenna unit to convert the channelized signalsbefore RF conversion and transmission.

In contrast, radio system signals are not specific to a particularchannel and may include a number of different channels. The radio systemsignals represent either digitized or analog spectrum and are one stepcloser to RF signals than the channelized signals. In exemplaryembodiments, the radio system signal is at an intermediate frequencythat maps to a large portion of RF spectrum including a number ofchannels. In exemplary embodiments, the radio system signals can simplybe up-converted from the intermediate frequency to radio frequency andtransmitted at an antenna unit as described below. Thus, the antennaunits do not need the capability of processing channelized signalsbefore RF conversion and transmission. Accordingly, in these exemplaryembodiments it doesn't matter what channels are sent to the antennaunits. In exemplary embodiments, the antenna unit communicates withsubscriber units using a first set of channels at first frequencies anda second set of channels at second frequencies. In exemplaryembodiments, the antenna unit communicates using different modulationand/or radio access technologies simultaneously.

FIGS. 1A-1D are block diagrams of exemplary embodiments of systems 100for measuring downlink and uplink delays in a distributed antenna systemunder test 101, labeled system 100A, system 100B, and system 100Crespectively.

FIG. 1A is a block diagram of an exemplary embodiment of a system 100Afor measuring downlink delays in a distributed antenna system under test101. Distributed antenna system under test includes a digital host 102and an antenna unit 104. System 100A includes a digital waveformgenerator 106A and a spectrum analyzer 108. The digital host 102 of thedistributed antenna system under test 101 is communicatively coupled tothe antenna unit 104 by a communication medium 112. In exemplaryembodiments, the communication medium 112 is at least one of an opticalfiber, coaxial cable, and twisted pair. The antenna unit 104 includes aradio frequency antenna 114.

The digital waveform generator 106A is communicatively coupled to thedigital host 102 of the distributed antenna system under test 101 by acommunication medium 110. The radio frequency antenna 114 of the antennaunit 104 of the distributed antenna system under test 101 iscommunicatively coupled to the spectrum analyzer 108 by a communicationmedium 116. The digital waveform generator 106A is also communicativelycoupled directly to the spectrum analyzer 108 through communicationmedium 118 without going through the distributed antenna system undertest 101.

The digital host 102 receives digital signals from the digital waveformgenerator 106A and communicates digital signals to the antenna unit 104.The antenna unit 104 receives digital signals from the digital host 102and converts the digital signals into radio frequency signals andtransmits them using the radio frequency antenna 114. The spectrumanalyzer 108 receives and analyzes the radio frequency signalstransmitted using radio frequency antenna 114. The digital waveformgenerator 106A generates a digital representation of a Gaussian pulseand applies that to a digital interface of the digital host 102. Thedigital waveform generator 106A marks the digital representation of theGaussian pulse with respect to a frame of digital data with a marker.The digital host propagates the Gaussian pulse to the antenna unit 104across the communication medium 112. The antenna unit 104 converts thedigital representation of the Gaussian pulse to a radio frequency signaland transmits it at the antenna. The spectrum analyzer 108 measures whenthe Gaussian pulse occurs in the radio frequency signal based on themarker. In exemplary embodiments, the Gaussian Pulse is used because theshape of the waveform is maintained (particularly the peak), even withmultiple stages of filtering (digital and RF), allowing for an accuratedelay measurement. In exemplary embodiments, the Gaussian Pulse providesminimal distortion in bandwidth limited radio frequency (RF) channels.

The system 100A is configured to determine a downlink propagation delayfor the distributed antenna system under test 101 between application ofthe digital representation of the Gaussian pulse at the digitalinterface of the digital host 102 and transmission of the radiofrequency signal at the radio frequency antenna 114. In exemplaryembodiments, the downlink propagation delay includes both intrinsicdelay of the digital host 102 and antenna unit 104 and downlinktransmission delay across the communication medium 112. In exemplaryembodiments, the system 100A is configured to determine the downlinktransmission delay across the communication medium 112 between thedigital host 102 and the antenna unit 104. In exemplary embodiments, thesystem 100A is further configured to subtract the downlink transmissiondelay from the downlink propagation delay to determine a total intrinsicdelay including first intrinsic delay of the digital host 102 and secondintrinsic delay of the antenna unit 104.

In exemplary embodiments, the digital waveform generator 106A isconfigured to provide the marker to the spectrum analyzer 108 viacommunication medium 118 separate from and bypassing the distributedantenna system under test 101. In exemplary embodiments, the digitalhost 102 is configured to receive digital signals selected from one of aCommon Public Radio Interface (CPRI) external device interface, an OpenBase Station Architecture Initiative (OBSAI) external device interface,and an Open Radio Interface (ORI) external device interface.

In exemplary embodiments, the communication medium 112 is an opticalfiber and the communication across the communication medium 112 isoptical. In these embodiments, an electrical to optical conversionoccurs at the digital host 102 and antenna unit 104. In otherembodiments, the communication medium 112 is a conductive cable (such ascoaxial cable, twisted pair, etc.) and the communication across thecommunication medium 112 is electrical. In exemplary embodiments, thecommunication across the communication medium 112 is digital. Inexemplary embodiments, the communication across the communication medium112 is analog. In exemplary embodiments, any mixture of optical,electrical, analog, and digital communication occurs across thecommunication medium 110. In exemplary embodiments, the antenna unit 104includes functionality to convert between digital and analog signals.

FIG. 1B is a block diagram of an exemplary embodiment of a system 100Bfor measuring downlink delays in a distributed antenna system under test101. Distributed antenna system under test includes a digital host 102and an antenna unit 104. System 100B includes a waveform generator 106,a digital to radio frequency (RF) converter 122, and a spectrum analyzer108. The digital host 102 of the distributed antenna system under test101 is communicatively coupled to the antenna unit 104 by acommunication medium 112. In exemplary embodiments, the communicationmedium 112 is at least one of an optical fiber, coaxial cable, andtwisted pair. The antenna unit 104 includes a radio frequency antenna114.

System 100B includes similar components and functionality to system100A, the difference being that system 100B includes a waveformgenerator 106 on the radio frequency antenna 114 side and a digital to(radio frequency) RF converter 122 and the spectrum analyzer 108 on thedigital host 102 side. The waveform generator 106 is communicativelycoupled to the radio frequency antenna 114 of the antenna unit 104 bythe communication medium 116. The digital host 102 of the distributedantenna system under test 101 is communicatively coupled to the digitalto RF converter 122 by the communication medium 110 and the digital toRF converter 122 is connected to the spectrum analyzer 108 by acommunication medium 124. The waveform generator 106 is alsocommunicatively coupled directly to the spectrum analyzer 108 throughthe communication medium 118 without going through the distributedantenna system under test 101.

The antenna unit 104 receives radio frequency signals from the waveformgenerator 106, converts them to digital signals, and communicates thedigital signals to the digital host 102. The digital host 102 receivesdigital signals from the antenna unit 104 and communicates them to thedigital to RF converter 122. The digital to RF converter 122 convertsthe digital signals to radio frequency (RF) signals and transmits the RFsignals to the spectrum analyzer 108. The spectrum analyzer 108 receivesand analyzes the RF signals received from the digital to RF converter122 based on the digital signals received from the digital host 102. Thewaveform generator 106 generates a Gaussian pulse and applies that tothe radio frequency antenna 114 of the antenna unit 104. The waveformgenerator 106 marks the Gaussian pulse with respect to a frame ofdigital data with a marker. The antenna unit 104 propagates the Gaussianpulse to the digital host 102 across the communication medium 112. Thedigital host 102 outputs the digital representation of the Gaussianpulse to the spectrum analyzer 108. The spectrum analyzer 108 measureswhen the Gaussian pulse occurs in the digital representation of theGaussian pulse based on the marker. In exemplary embodiments, theGaussian Pulse is used because the shape of the waveform is maintained(particularly the peak), even with multiple stages of filtering (digitaland RF), allowing for an accurate delay measurement. In exemplaryembodiments, the Gaussian Pulse provides minimal distortion in bandwidthlimited radio frequency (RF) channels.

The system 100B is configured to determine an uplink propagation delayfor the distributed antenna system under test 101 between application ofthe Gaussian pulse at the radio frequency antenna 114 of the antennaunit 104 and output of the digital representation of the Gaussian pulseat the digital interface of the digital host 102. In exemplaryembodiments, the uplink propagation delay includes both intrinsic delayof the digital host 102 and antenna unit 104 and uplink transmissiondelay across the communication medium 112. In exemplary embodiments, thesystem 100B is configured to determine the uplink transmission delayacross the communication medium 112 between the digital host 102 and theantenna unit 104. In exemplary embodiments, the system 100B isconfigured to determine the delay through the digital to RF converter122. In exemplary embodiments, the system 100B is further configured tosubtract the uplink transmission delay and the delay through the digitalto RF converter 122 from the uplink propagation delay to determine atotal uplink intrinsic delay including first intrinsic delay of thedigital host 102 and second intrinsic delay of the antenna unit 104.

In exemplary embodiments, the waveform generator 106 is configured toprovide the marker to the spectrum analyzer 108 via communication medium118 separate from and bypassing the distributed antenna system undertest 101. In exemplary embodiments, the digital host 102 is configuredto output digital signals selected from one of a Common Public RadioInterface (CPRI) external device interface, an Open Base StationArchitecture Initiative (OBSAI) external device interface, and an OpenRadio Interface (ORI) external device interface.

In exemplary embodiments, the communication medium 112 is an opticalfiber and the communication across the communication medium 112 isoptical. In these embodiments, an electrical to optical conversionoccurs at the digital host 102 and antenna unit 104. In otherembodiments, the communication medium 112 is a conductive cable (such ascoaxial cable, twisted pair, etc.) and the communication across thecommunication medium 112 is electrical. In exemplary embodiments, thecommunication across the communication medium 112 is digital. Inexemplary embodiments, the communication across the communication medium112 is analog. In exemplary embodiments, any mixture of optical,electrical, analog, and digital communication occurs across thecommunication medium 110. In exemplary embodiments, the antenna unit 104includes functionality to convert between digital and analog signals.

FIG. 1C is a block diagram of an exemplary embodiment of a system 100Cfor measuring delays in a distributed antenna system under test 101.Distributed antenna system under test 101 includes a digital host 102and an antenna unit 104. System 100C includes a waveform generator 106and a spectrum analyzer 108. The digital host 102 of the distributedantenna system under test 101 is communicatively coupled to the antennaunit 104 by a communication medium 112. In exemplary embodiments, thecommunication medium 112 is at least one of an optical fiber, coaxialcable, and twisted pair. The antenna unit 104 includes a radio frequencyantenna 114.

System 100C includes similar components and functionality to systems100A and 100B, the difference being that system 100C includes both awaveform generator 106 and a spectrum analyzer 108 on the radiofrequency antenna 114 side and that the digital host 102 includes adigital loopback. The waveform generator 106 is communicatively coupledto the radio frequency antenna 114 of the antenna unit 104 by thecommunication medium 116. In addition, the radio frequency antenna 114of the antenna unit 104 of the distributed antenna system under test 101is communicatively coupled to the spectrum analyzer 108 by acommunication medium 126. The waveform generator 106 is alsocommunicatively coupled directly to the spectrum analyzer 108 throughcommunication medium 118 without going through the distributed antennasystem under test 101.

The antenna unit 104 receives radio frequency (RF) signals from thewaveform generator 106, converts them to digital signals, andcommunicates the digital signals to the digital host 102. The digitalhost 102 receives digital signals from the antenna unit 104 and loopsthem back to the antenna unit 104. The antenna unit 104 receives thelooped-back digital signals from digital host 102, converts them toradio frequency (RF) signals and transmits the RF signals to thespectrum analyzer 108. The spectrum analyzer 108 receives and analyzesthe RF signals received from the antenna unit 104 via the radiofrequency antenna 114. The waveform generator 106 generates a Gaussianpulse and applies that to the radio frequency antenna 114 of the antennaunit 104. The waveform generator 106 marks the Gaussian pulse withrespect to a frame of digital data with a marker. The antenna unit 104converts the Gaussian pulse to a digital representation and propagatesthe digital representation of the Gaussian pulse to the digital host 102across the communication medium 112. The digital host 102 loops-back thedigital representation of the Gaussian pulse to the antenna unit 104.The antenna unit 104 converts the looped-back digital representation ofthe Gaussian pulse back to an looked-back analog representation of theGaussian pulse and communicates it to the spectrum analyzer 108 via theradio frequency antenna 114. The spectrum analyzer 108 measures when theGaussian pulse occurs in the looped-back analog representation of theGaussian pulse based on the marker. In exemplary embodiments, theGaussian Pulse is used because the shape of the waveform is maintained(particularly the peak), even with multiple stages of filtering (digitaland RF), allowing for an accurate delay measurement. In exemplaryembodiments, the Gaussian Pulse provides minimal distortion in bandwidthlimited radio frequency (RF) channels.

The system 100C is configured to determine a round-trip loopbackpropagation delay for the distributed antenna system under test 101between application of the Gaussian pulse at the radio frequency antenna114 of the antenna unit 104 and output of the looped-back analogrepresentation of the Gaussian pulse at the radio frequency antenna 114of the antenna unit 104. In exemplary embodiments, the round-triploopback propagation delay includes both intrinsic delay of the digitalhost 102 and antenna unit 104 and transmission delay across thecommunication medium 112. In exemplary embodiments, the system 100B isconfigured to determine the uplink transmission delay across thecommunication medium 112 between the digital host 102 and the antennaunit 104. In exemplary embodiments, the system 100B is configured todetermine both the round-trip loopback propagation delay and thedownlink delay. In some implementations, the downlink delay iscalculated using the system 100A described above. In exemplaryembodiments, the system 100B is further configured to subtract thedownlink delay and the uplink transmission delay across thecommunication medium 112 from the round trip propagation delay todetermine a total uplink intrinsic delay including first intrinsic delayof the digital host 102 and second intrinsic delay of the antenna unit104.

In exemplary embodiments, the waveform generator 106 is configured toprovide the marker to the spectrum analyzer 108 via communication medium118 separate from and bypassing the distributed antenna system undertest 101. In exemplary embodiments, the digital host 102 is configuredto output digital signals selected from one of a Common Public RadioInterface (CPRI) external device interface, an Open Base StationArchitecture Initiative (OBSAI) external device interface, and an OpenRadio Interface (ORI) external device interface.

In exemplary embodiments, the communication medium 112 is an opticalfiber and the communication across the communication medium 112 isoptical. In these embodiments, an electrical to optical conversionoccurs at the digital host 102 and antenna unit 104. In otherembodiments, the communication medium 112 is a conductive cable (such ascoaxial cable, twisted pair, etc.) and the communication across thecommunication medium 112 is electrical. In exemplary embodiments, thecommunication across the communication medium 112 is digital. Inexemplary embodiments, the communication across the communication medium112 is analog. In exemplary embodiments, any mixture of optical,electrical, analog, and digital communication occurs across thecommunication medium 110. In exemplary embodiments, the antenna unit 104includes functionality to convert between digital and analog signals.

FIG. 1D is a block diagram of an exemplary embodiment of a system 100Dfor measuring delays in a distributed antenna system under test 101.Distributed antenna system under test 101 includes a digital host 102and an antenna unit 104. System 100D includes a waveform generator 106and a spectrum analyzer 108. The digital host 102 of the distributedantenna system under test 101 is communicatively coupled to the antennaunit 104 by a communication medium 112. In exemplary embodiments, thecommunication medium 112 is at least one of an optical fiber, coaxialcable, and twisted pair. The antenna unit 104 includes a radio frequencyantenna 114.

System 100D includes similar components and functionality to systems100A, 100B, and 100C, the difference being that system 100D includesboth a waveform generator 106 and a spectrum analyzer 108 on the radiofrequency antenna 114 side and a digital waveform generator 106A on thedigital host 102 side and that the digital host 102 includes a digitalloopback. Accordingly, the system 100D is configured to determine theround trip delay in the same way as system 100C described above and alsothe downlink delay in the same way as system 100B described above. Inexemplary embodiments, the uplink delay is then calculated bysubtracting the downlink delay (and the transport delay acrosscommunication medium 112) from the round trip delay.

FIG. 2 is a block diagram of an exemplary embodiment of digital host102.

Digital host 102 includes a signal conversion module 202, an externaldigital interface 204, an antenna system digital interface 206, anoptional processor 208, an optional memory 210, and an optional powersupply 212. In exemplary embodiments, signal conversion module 202 iscommunicatively coupled to either a waveform generator 106 or a spectrumanalyzer 108 through the external digital interface 204. Signalconversion module 202 is also communicatively coupled to at least onecommunication medium 112 by antenna system digital interface 206. Inexemplary embodiments, the communication medium 112 is an opticalcommunication link across a fiber optic cable, though it can also beother types of wired or wireless links in other embodiments. Inexemplary embodiments, the signal conversion module 202 and/or portionsof the external digital interface 204 and/or the antenna system digitalinterface 206 are implemented using optional processor 208 and optionalmemory 210. In exemplary embodiments, the optional power supply 212provides power to the various elements of the digital host 102.

When measuring the downlink delay, the external digital interface 204 isconfigured to receive the digital representation of the Gaussian pulsefrom a waveform generator 106. The signal conversion module 202 isconfigured to convert the received Gaussian pulse to a downlink radiosystem signal. In exemplary embodiments, the signal conversion module202 and/or the antenna system digital interface 206 converts the radiosystem signal from electrical signals to optical signals for output oncommunication medium 112. In other embodiments, the radio system signalis transported using a conductive communication medium, such as coaxialcable or twisted pair, and the optical conversion is not necessary. Theantenna system digital interface 206 is configured to communicate thedownlink radio system signal on communication medium 112.

When measuring the uplink delay, antenna system digital interface 206 isconfigured to receive an uplink digital representation of a Gaussianpulse from communication medium 112. In exemplary embodiments wherecommunication medium 112 is an optical medium, the antenna systemdigital interface 206 and/or the signal conversion module 202 isconfigured to convert the uplink radio system signal between receivedoptical signals and electrical signals. In other embodiments, the radiosystem signal is transported using a conductive communication medium,such as coaxial cable or twisted pair, and the optical conversion is notnecessary. The signal conversion module 202 is further configured toconvert the uplink radio system signal to uplink signals. Externaldigital interface 204 is configured to communicate the uplink digitalrepresentation of the Gaussian pulse to a spectrum analyzer 108.

When measuring the round trip delay, the external digital interface 204is configured as a loop back. In exemplary embodiments, the antennasystem digital interface 206 is configured to receive an uplink digitalrepresentation of a Gaussian pulse from communication medium 112. Inexemplary embodiments where communication medium 112 is an opticalmedium, the antenna system digital interface 206 and/or the signalconversion module 202 is configured to convert the uplink radio systemsignal between received optical signals and electrical signals. In otherembodiments, the radio system signal is transported using a conductivecommunication medium, such as coaxial cable or twisted pair, and theoptical conversion is not necessary. The signal conversion module 202 isfurther configured to convert the uplink radio system signal to uplinksignals. External digital interface 204 is configured to loop back theuplink digital representation of the Gaussian pulse into the downlinkback to the signal conversion module 202. In exemplary embodiments, thesignal conversion module 202 is configured to convert the receivedGaussian pulse to a downlink radio system signal. In exemplaryembodiments, the signal conversion module 202 and/or the antenna systemdigital interface 206 converts the radio system signal from electricalsignals to optical signals for output on communication medium 112. Inother embodiments, the radio system signal is transported using aconductive medium, such as coaxial cable or twisted pair, and theoptical conversion is not necessary. The antenna system digitalinterface 206 is configured to communicate the downlink radio systemsignal on communication medium 112.

FIG. 3 is a block diagram of an exemplary embodiment of an antenna unit104. The antenna unit 104 includes a signal conversion module 302, anantenna system digital interface 304, an antenna side interface 306, anoptional processor 308, optional memory 310, and optional power supply312. In exemplary embodiments, signal conversion module 302, antennasystem digital interface 304, and/or the antenna side interface 306 areimplemented at least in part by optional processor 308 and optionalmemory 310. In exemplary embodiments, optional power supply 312 is usedto power the various components of the antenna unit 104.

When measuring downlink delay and round trip delay, the antenna systemdigital interface 304 is configured to receive a digital representationof the Gaussian pulse from the digital host 102 across communicationmedium 112. The signal conversion module 302 is configured to convertthe received Gaussian pulse to a downlink radio frequency signalincluding the Gaussian pulse. The antenna side interface 306 isconfigured to communicate the downlink frequency signal having theGaussian pulse using the radio frequency antenna 114 to a spectrumanalyzer 108.

When measuring uplink delay and round trip delay, antenna side interface306 is configured to receive an uplink radio frequency signal having aGaussian pulse from a waveform generator 106. The signal conversionmodule 302 is configured to convert the received Gaussian pulse to anuplink digital representation of the Gaussian pulse in a digital signalcommunicated to the digital host across the communication medium 112 viaantenna system digital interface 304.

In exemplary embodiments where communication medium 112 is an opticalmedium, the antenna system digital interface 304 and/or the signalconversion module 302 is configured to convert the uplink radio systemsignal between received electrical signals and optical signals. In otherembodiments, the radio system signal is transported using a conductivecommunication medium, such as coaxial cable or twisted pair, and theoptical conversion is not necessary.

FIG. 4 is a flow diagram illustrating one exemplary embodiment of amethod 400 for measuring downlink delay in a radio system. Exemplarymethod 400 begins at block 402 with applying a digital representation ofa Gaussian pulse to a digital interface of the radio system. Exemplarymethod 400 proceeds to block 404 with marking the digital representationof the Gaussian pulse with respect to a frame of digital data with amarker. Exemplary method 400 proceeds to block 406 with propagating theGaussian pulse in the radio system to an antenna. The radio system isconfigured to convert the digital representation of the Gaussian pulseto a radio frequency signal transmitted at the antenna. Exemplary method400 proceeds to block 408 with measuring when the Gaussian pulse occursin the radio frequency signal based on the marker. Exemplary method 400proceeds to block 410 with determining a downlink propagation delay forthe radio system between application of the digital representation ofthe Gaussian pulse at the digital interface and transmission of theradio frequency signal at the antenna. In exemplary embodiments, thedownlink propagation delay includes intrinsic delay and downlinktransmission delay across a communication medium between two componentsof the radio system. In exemplary embodiments, the downlink propagationdelay includes a first intrinsic delay within the digital interface tothe radio system, a second intrinsic delay within an antenna unitcommunicatively coupled to the antenna and remotely coupled with thedigital interface across a communication medium, and wherein thedownlink propagation delay further includes a downlink transmissiondelay across the communication medium between the digital interface andthe antenna unit.

In exemplary embodiments, method 400 further includes measuring thedownlink transmission delay across the communication medium between thedigital interface and the antenna unit and subtracting the downlinktransmission delay from the downlink propagation delay to determine atotal intrinsic delay including the first intrinsic delay and the secondintrinsic delay. In exemplary embodiments, method 400 further includesgenerating the Gaussian pulse. In exemplary embodiments, method 400further includes converting the Gaussian pulse to a digitalrepresentation of the Gaussian pulse. In exemplary embodiments,measuring when the Gaussian pulse occurs in the radio frequency signalbased on the marker occurs using a spectrum analyzer. In exemplaryembodiments, method 400 includes providing the marker from a firstdevice used to generate the digital representation of the Gaussian pulseto a second device used to analyze the radio frequency signal todetermine when the Gaussian pulse occurs. In exemplary embodiments,propagating the Gaussian pulse in the radio system to the antenna occursacross an optical fiber. In exemplary embodiments, the digital interfaceis part of a host unit, the antenna is part of an antenna unit remote tothe host unit, and the host unit and the antenna unit arecommunicatively coupled via a wired communication medium. In exemplaryembodiments, the wired communication medium is at least one of anoptical fiber, coaxial cable, and twisted pair.

FIG. 5 is a flow diagram illustrating one exemplary embodiment of amethod 500 for measuring uplink delay in a radio system. Exemplarymethod 500 begins at block 502 with applying a Gaussian pulse to a radiofrequency signal input at an antenna. Exemplary method 500 proceeds toblock 504 with marking the Gaussian pulse with respect to a frame ofdigital data with a marker. Exemplary method 500 proceeds to block 506with propagating the Gaussian pulse in the radio system to a digitalinterface of the radio system, the radio system configured to convertthe Gaussian pulse to a digital representation of the Gaussian pulsecommunicated at the digital interface in a digital signal. Exemplarymethod 500 proceeds to block 508 with measuring when the Gaussian pulseoccurs in the digital signal based on the marker. Exemplary method 500proceeds to block 510 with determining an uplink propagation delay forthe radio system between application of the Gaussian pulse to the radiofrequency signal input at the antenna and communication of the digitalrepresentation of the Gaussian pulse at the digital interface in thedigital signal.

In exemplary embodiments, the uplink propagation delay includesintrinsic delay and uplink transmission delay across a communicationmedium between two components of the radio system. In exemplaryembodiments, the uplink propagation delay includes a first uplinkintrinsic delay within an antenna unit communicatively coupled to theantenna and remotely coupled with the digital interface across acommunication medium. In exemplary embodiments, the uplink propagationdelay further includes a second uplink intrinsic delay within thedigital interface to the radio system. In exemplary embodiments, thedownlink propagation delay further includes an uplink transmission delayacross the communication medium between the antenna unit and the digitalinterface.

In exemplary embodiments, method 500 further includes measuring theuplink transmission delay across the communication medium between theantenna unit and the digital interface and subtracting the uplinktransmission delay from the uplink propagation delay to determine atotal uplink intrinsic delay including the first uplink intrinsic delayand the second uplink intrinsic delay. In exemplary embodiments, method500 further includes generating the Gaussian pulse. In exemplaryembodiments, method 500 further includes converting the digitalrepresentation of the Gaussian pulse back to the Gaussian pulse. Inexemplary embodiments, measuring when the Gaussian pulse occurs in thedigital signal based on the marker occurs using a spectrum analyzer.

In exemplary embodiments, method 500 further includes providing themarker from a first device used to generate the Gaussian pulse to asecond device used to analyze the digital signal to determine when theGaussian pulse occurs. In exemplary embodiments, propagating theGaussian pulse in the radio system to the digital interface occursacross an optical fiber. In exemplary embodiments, the digital interfaceis part of a host unit, the antenna is part of an antenna unit remote tothe host unit, and the host unit and the antenna unit arecommunicatively coupled via a wired communication medium. In exemplaryembodiments, the wired communication medium is at least one of anoptical fiber, coaxial cable, and twisted pair.

FIGS. 6A-6B show a flow diagram illustrating one exemplary embodiment ofa method 600 for measuring delay in a radio system. Exemplary method 600begins at block 602 with applying a first Gaussian pulse to a radiofrequency signal input at an antenna. Exemplary method 600 proceeds toblock 604 with marking the first Gaussian pulse with respect to a firstframe of digital data with a first marker. Exemplary method 600 proceedsto block 606 with propagating the first Gaussian pulse in a radio systemto a digital interface of the radio system, the radio system configuredto convert the first Gaussian pulse to a first digital representation ofthe first Gaussian pulse communicated at the digital interface in afirst digital signal.

Exemplary method 600 proceeds to block 608 with looping back the firstGaussian pulse in the radio system from the digital interface of theradio system to a radio frequency signal output at the antenna, theradio system configured to convert the first digital representation ofthe first Gaussian pulse to a first radio frequency signal having thefirst Gaussian pulse transmitted at the antenna. Exemplary method 600proceeds to block 610 with measuring when the first Gaussian pulseoccurs in the first radio frequency signal based on the first marker.Exemplary method 600 proceeds to block 612 with determining a round trippropagation delay for the radio system between application of the firstGaussian pulse to the radio frequency signal input at the antenna andcommunication of the first radio frequency signal having the firstGaussian pulse transmitted at the radio frequency signal output at theantenna.

Exemplary method 600 proceeds to optional block 614 with applying asecond digital representation of a second Gaussian pulse to the digitalinterface of the radio system. Exemplary method 600 proceeds to optionalblock 616 with marking the second digital representation of the secondGaussian pulse with respect to a second frame of digital data with asecond marker. Exemplary method 600 proceeds to optional block 618 withpropagating the second Gaussian pulse in the radio system to theantenna, the radio system configured to convert the second digitalrepresentation of the second Gaussian pulse to a second radio frequencysignal transmitted at the antenna. Exemplary method 600 proceeds tooptional block 620 with measuring when the second Gaussian pulse occursin the second radio frequency signal based on the second marker.

Exemplary method 600 proceeds to optional block 622 with determining adownlink propagation delay for the radio system between application ofthe second digital representation of the second Gaussian pulse at thedigital interface and transmission of the second radio frequency signalat the antenna. Exemplary method 600 proceeds to optional block 624 withdetermining an uplink propagation delay for the radio system bysubtracting the downlink propagation delay for the radio system from theround trip propagation delay for the radio system.

Any of the processors described above may include or function withsoftware programs, firmware or other computer readable instructions forcarrying out various methods, process tasks, calculations, and controlfunctions, described herein. These instructions are typically stored onany appropriate computer readable medium used for storage of computerreadable instructions or data structures. The computer readable mediumcan be implemented as any available media that can be accessed by ageneral purpose or special purpose computer or processor, or anyprogrammable logic device. Suitable processor-readable media may includestorage or memory media such as magnetic or optical media. For example,storage or memory media may include conventional hard disks, CompactDisk-Read Only Memory (CD-ROM), volatile or non-volatile media such asRandom Access Memory (RAM) (including, but not limited to, SynchronousDynamic Random Access Memory (SDRAM), Double Data Rate (DDR) RAM, RAMBUSDynamic RAM (RDRAM), Static RAM (SRAM), etc.), Read Only Memory (ROM),Electrically Erasable Programmable ROM (EEPROM), and flash memory, etc.Suitable processor-readable media may also include transmission mediasuch as electrical, electromagnetic, or digital signals, conveyed via acommunication medium such as a network and/or a wireless link.

Although specific embodiments have been illustrated and describedherein, it will be appreciated by those of ordinary skill in the artthat any arrangement, which is calculated to achieve the same purpose,may be substituted for the specific embodiments shown. Therefore, it ismanifestly intended that this invention be limited only by the claimsand the equivalents thereof.

Example Embodiments

Example 1 includes a method for measuring downlink delay in a radiosystem, comprising: applying a digital representation of a Gaussianpulse to a digital interface of the radio system; marking the digitalrepresentation of the Gaussian pulse with respect to a frame of digitaldata with a marker; propagating the Gaussian pulse in the radio systemto an antenna, the radio system configured to convert the digitalrepresentation of the Gaussian pulse to a radio frequency signaltransmitted at the antenna; measuring when the Gaussian pulse occurs inthe radio frequency signal based on the marker; and determining adownlink propagation delay for the radio system between application ofthe digital representation of the Gaussian pulse at the digitalinterface and transmission of the radio frequency signal at the antenna.

Example 2 includes the method of Example 1, wherein the downlinkpropagation delay includes intrinsic delay and transmission delay acrossa communication medium between two components of the radio system.

Example 3 includes the method of any of Examples 1-2, wherein thedownlink propagation delay includes a first intrinsic delay within thedigital interface to the radio system; wherein the downlink propagationdelay includes a second intrinsic delay within an antenna unitcommunicatively coupled to the antenna and remotely coupled with thedigital interface across a communication medium; and wherein thedownlink propagation delay further includes a transmission delay acrossthe communication medium between the digital interface and the antennaunit.

Example 4 includes the method of Example 3, further comprising:measuring the transmission delay across the communication medium betweenthe digital interface and the antenna unit; and subtracting thetransmission delay from the downlink propagation delay to determine atotal intrinsic delay including the first intrinsic delay and the secondintrinsic delay.

Example 5 includes the method of any of Examples 1-4, furthercomprising: generating the Gaussian pulse.

Example 6 includes the method of any of Examples 1-5, furthercomprising: converting the Gaussian pulse to a digital representation ofthe Gaussian pulse.

Example 7 includes the method of any of Examples 1-6, wherein measuringwhen the Gaussian pulse occurs in the radio frequency signal based onthe marker occurs using a spectrum analyzer.

Example 8 includes the method of any of Examples 1-7, further comprisingproviding the marker from a first device used to generate the digitalrepresentation of the Gaussian pulse to a second device used to analyzethe radio frequency signal to determine when the Gaussian pulse occurs.

Example 9 includes the method of any of Examples 1-8, whereinpropagating the Gaussian pulse in the radio system to the antenna occursacross an optical fiber.

Example 10 includes the method of any of Examples 1-9, wherein thedigital interface is part of a host unit; wherein the antenna is part ofan antenna unit remote to the host unit; and wherein the host unit andthe antenna unit are communicatively coupled via a wired communicationmedium.

Example 11 includes the method of Example 10, wherein the wiredcommunication medium is at least one of an optical fiber, coaxial cable,and twisted pair.

Example 12 includes a system for measuring downlink delay in a radiosystem, comprising: a waveform generator configured to generate adigital representation of a Gaussian pulse and apply it to a digitalinterface of the radio system; wherein the waveform generator is furtherconfigured to mark the digital representation of the Gaussian pulse withrespect to a frame of digital data with a marker; wherein the radiosystem is configured to propagate the Gaussian pulse and convert thedigital representation of the Gaussian pulse to a radio frequency signaltransmitted at an antenna; a spectrum analyzer configured to measurewhen the Gaussian pulse occurs in the radio frequency signal based onthe marker; and wherein the system is configured to determine a downlinkpropagation delay for the radio system between application of thedigital representation of the Gaussian pulse at the digital interfaceand transmission of the radio frequency signal at the antenna.

Example 13 includes the system of Example 12, wherein the downlinkpropagation delay includes intrinsic delay and transmission delay acrossa communication medium between two components of the radio system.

Example 14 includes the system of any of Examples 12-13, wherein thedownlink propagation delay includes a first intrinsic delay within thedigital interface to the radio system; wherein the downlink propagationdelay includes a second intrinsic delay within an antenna unitcommunicatively coupled to the antenna and remotely coupled with thedigital interface across a communication medium; and wherein thedownlink propagation delay further includes a transmission delay acrossthe communication medium between the digital interface and the antennaunit.

Example 15 includes the system of Example 14, further comprising:wherein the system is further configured to determine the transmissiondelay across the communication medium between the digital interface andthe antenna unit; and wherein the system is further configured tosubtract the transmission delay from the downlink propagation delay todetermine a total intrinsic delay including the first intrinsic delayand the second intrinsic delay.

Example 16 includes the system of any of Examples 12-15, wherein thewaveform generator is configured to provide the marker to the spectrumanalyzer via a communication medium separate from the radio system.

Example 17 includes the system of any of Examples 12-16, wherein theradio system includes a digital host having the digital interface;wherein the radio system includes an antenna unit having the antenna;wherein the digital host is communicatively coupled to the antenna unitvia a communication medium.

Example 18 includes the system of Example 17, wherein the digital hostis configured to communicate the Gaussian pulse to the antenna unit viathe communication medium; and wherein the antenna unit is configured toconvert the digital representation of the Gaussian pulse to a radiofrequency signal transmitted at the antenna.

Example 19 includes the system of any of Examples 17-18, wherein thecommunication medium is at least one of an optical fiber, coaxial cable,and twisted pair.

Example 20 includes a method for measuring uplink delay in a radiosystem, comprising: applying a Gaussian pulse to a radio frequencysignal input at an antenna; marking the Gaussian pulse with respect to aframe of digital data with a marker; propagating the Gaussian pulse inthe radio system to a digital interface of the radio system, the radiosystem configured to convert the Gaussian pulse to a digitalrepresentation of the Gaussian pulse communicated at the digitalinterface in a digital signal; measuring when the Gaussian pulse occursin the digital signal based on the marker; and determining an uplinkpropagation delay for the radio system between application of theGaussian pulse to the radio frequency signal input at the antenna andcommunication of the digital representation of the Gaussian pulse at thedigital interface in the digital signal.

Example 21 includes the method of Example 20, wherein the uplinkpropagation delay includes intrinsic delay and transmission delay acrossa communication medium between two components of the radio system.

Example 22 includes the method of any of Examples 20-21, wherein theuplink propagation delay includes a first intrinsic delay within anantenna unit communicatively coupled to the antenna and remotely coupledwith the digital interface across a communication medium; wherein theuplink propagation delay further includes a second intrinsic delay

within the digital interface to the radio system; and wherein the uplinkpropagation delay further includes a transmission delay across thecommunication medium between the antenna unit and the digital interface.

Example 23 includes the method of Example 22, further comprising:measuring the digital transmission delay across the communication mediumbetween the antenna unit and the digital interface; and subtracting thedigital transmission delay from the uplink propagation delay todetermine a total intrinsic delay including the first intrinsic delayand the second intrinsic delay.

Example 24 includes the method of any of Examples 20-23, furthercomprising: generating the Gaussian pulse.

Example 25 includes the method of any of Examples 20-24, furthercomprising: converting the digital representation of the Gaussian pulseback to the Gaussian pulse.

Example 26 includes the method of any of Examples 20-25, whereinmeasuring when the Gaussian pulse occurs in the digital signal based onthe marker occurs using a spectrum analyzer.

Example 27 includes the method of any of Examples 20-26, furthercomprising providing the marker from a first device used to generate theGaussian pulse to a second device used to analyze the digital signal todetermine when the Gaussian pulse occurs.

Example 28 includes the method of any of Examples 20-27, whereinpropagating the Gaussian pulse in the radio system to the digitalinterface occurs across an optical fiber.

Example 29 includes the method of any of Examples 20-28, wherein thedigital interface is part of a host unit; wherein the antenna is part ofan antenna unit remote to the host unit; and wherein the host unit andthe antenna unit are communicatively coupled via a wired communicationmedium.

Example 30 includes the method of any of Examples 20-29, wherein thewired communication medium is at least one of an optical fiber, coaxialcable, and twisted pair.

Example 31 includes a system for measuring uplink delay in a radiosystem, comprising: a waveform generator configured to generate aGaussian pulse and apply it to an antenna of the radio system; whereinthe waveform generator is further configured to mark the Gaussian pulsewith respect to a frame of digital data with a marker; wherein the radiosystem is configured to propagate the Gaussian pulse and convert theGaussian pulse to a digital representation of the Gaussian pulse outputat a digital interface of the radio system; a spectrum analyzerconfigured to measure when the digital representation of the Gaussianpulse occurs in a digital signal output from the digital interface ofthe radio system; and wherein the system is configured to determine anuplink propagation delay for the radio system between application of theGaussian pulse at the antenna of the radio system and output of thedigital signal at the digital interface of the radio system.

Example 32 includes the system of Example 31, wherein the uplinkpropagation delay includes intrinsic delay and transmission delay acrossa communication medium between two components of the radio system.

Example 33 includes the system of any of Examples 31-32, wherein theuplink propagation delay includes a first intrinsic delay within thedigital interface to the radio system; wherein the uplink propagationdelay includes a second intrinsic delay within an antenna unitcommunicatively coupled to the antenna and remotely coupled with thedigital interface across a communication medium; and wherein the uplinkpropagation delay further includes a transmission delay across thecommunication medium between the digital interface and the antenna unit.

Example 34 includes the system of Example 33, further comprising:wherein the system is further configured to determine the uplinktransmission delay across the communication medium between the digitalinterface and the antenna unit; and wherein the system is furtherconfigured to subtract the uplink transmission delay from the uplinkpropagation delay to determine a total intrinsic delay including thefirst intrinsic delay and the second intrinsic delay.

Example 35 includes the system of any of Examples 31-34, wherein thewaveform generator is configured to provide the marker to the spectrumanalyzer via a communication medium separate from the radio system.

Example 36 includes the system of any of Examples 31-35, wherein theradio system includes a digital host having the digital interface;wherein the radio system includes an antenna unit having the antenna;wherein the digital host is communicatively coupled to the antenna unitvia a communication medium.

Example 37 includes the system of Example 36, wherein the antenna unitis configured to communicate the digital Gaussian pulse to the digitalhost via the communication medium; and wherein the antenna unit isconfigured to convert a radio frequency signal received at the antennaand including the Gaussian pulse to a digital representation of theGaussian pulse output at the digital interface.

Example 38 includes the system of any of Examples 36-37, wherein thecommunication medium is at least one of an optical fiber, coaxial cable,and twisted pair.

Example 39 includes a method for measuring delay in a radio system,comprising: applying a first Gaussian pulse to a radio frequency signalinput at an antenna; marking the first Gaussian pulse with respect to afirst frame of digital data with a first marker; propagating the firstGaussian pulse in the radio system to a digital interface of the radiosystem, the radio system configured to convert the first Gaussian pulseto a first digital representation of the first Gaussian pulsecommunicated at the digital interface in a first digital signal; loopingback the first Gaussian pulse in the radio system from the digitalinterface of the radio system to a radio frequency signal output at theantenna, the radio system configured to convert the first digitalrepresentation of the first Gaussian pulse to a first radio frequencysignal having the first Gaussian pulse transmitted at the antenna;measuring when the first Gaussian pulse occurs in the first radiofrequency signal based on the first marker; and determining a round trippropagation delay for the radio system between application of the firstGaussian pulse to the radio frequency signal input at the antenna andcommunication of the first radio frequency signal having the firstGaussian pulse transmitted at the radio frequency signal output at theantenna.

Example 40 includes the method of Example 39, further comprising:applying a second digital representation of a second Gaussian pulse tothe digital interface of the radio system; marking the second digitalrepresentation of the second Gaussian pulse with respect to a secondframe of digital data with a second marker; propagating the secondGaussian pulse in the radio system to the antenna, the radio systemconfigured to convert the second digital representation of the secondGaussian pulse to a second radio frequency signal transmitted at theantenna; measuring when the second Gaussian pulse occurs in the secondradio frequency signal based on the second marker; and determining adownlink propagation delay for the radio system between application ofthe second digital representation of the second Gaussian pulse at thedigital interface and transmission of the second radio frequency signalat the antenna.

Example 41 includes the method of Example 40, further comprising:determining an uplink propagation delay for the radio system bysubtracting the downlink propagation delay for the radio system from theround trip propagation delay for the radio system.

Example 42 includes the method of Example 41, wherein the uplinkpropagation delay includes intrinsic delay and transmission delay acrossa communication medium between two components of the radio system.

Example 43 includes the method of any of Examples 41-42, wherein theuplink propagation delay includes a first uplink intrinsic delay withinan antenna unit communicatively coupled to the antenna and remotelycoupled with the digital interface across a communication medium;wherein the uplink propagation delay further includes a second uplinkintrinsic delay within the digital interface to the radio system; andwherein the uplink propagation delay further includes a transmissiondelay across the communication medium between the antenna unit and thedigital interface.

Example 44 includes the method of Example 43, further comprising:measuring the digital transmission delay across the communication mediumbetween the antenna unit and the digital interface; and subtracting thedigital transmission delay from the uplink propagation delay todetermine a total uplink intrinsic delay including the first uplinkintrinsic delay and the second uplink intrinsic delay.

Example 45 includes the method of any of Examples 39-44, furthercomprising: generating the first Gaussian pulse.

Example 46 includes the method of any of Examples 39-45, whereinmeasuring when the Gaussian pulse occurs in the digital signal based onthe marker occurs using a spectrum analyzer.

Example 47 includes the method of any of Examples 39-46, furthercomprising providing the first marker from a first device used togenerate the first Gaussian pulse to a second device used to analyze thefirst radio frequency signal to determine when the first Gaussian pulseoccurs.

Example 48 includes the method of any of Examples 39-47, whereinpropagating the Gaussian pulse in the radio system to the digitalinterface occurs across an optical fiber.

Example 49 includes the method of any of Examples 39-48, wherein thedigital interface is part of a host unit; wherein the antenna is part ofan antenna unit remote to the host unit; and wherein the host unit andthe antenna unit are communicatively coupled via a wired communicationmedium.

Example 50 includes the method of Example 49, wherein the wiredcommunication medium is at least one of an optical fiber, coaxial cable,and twisted pair.

Example 51 includes a system for measuring delay in a radio system,comprising: a first waveform generator configured to generate a firstGaussian pulse and to apply the first Gaussian pulse to an antenna ofthe radio system; wherein the first waveform generator is furtherconfigured to mark the first Gaussian pulse with respect to a firstframe of digital data with a first marker; wherein the radio system isconfigured to propagate the first Gaussian pulse and convert the firstGaussian pulse to a first digital representation of the first Gaussianpulse output at a digital interface of the radio system; wherein theradio system is further configured to loop back the first Gaussian pulsein the radio system from the digital interface of the radio system to aradio frequency signal output at the antenna and to convert the firstdigital representation of the first Gaussian pulse to a first radiofrequency signal having the first Gaussian pulse transmitted at theantenna; a spectrum analyzer configured to measure when the firstGaussian pulse occurs in the first radio frequency signal output at theantenna based on the first marker; wherein the system is configured todetermine a round trip propagation delay for the radio system betweenapplication of the first Gaussian pulse to the radio frequency signalinput at the antenna and communication of the first radio frequencysignal having the first Gaussian pulse transmitted at the radiofrequency signal output at the antenna.

Example 52 includes the system of Example 51, further comprising: asecond digital waveform generator configured to generate a seconddigital representation of a second Gaussian pulse and to apply thesecond digital representation of the second Gaussian pulse to thedigital interface of the radio system; wherein the second waveformgenerator is further configured to mark the second digitalrepresentation of the second Gaussian pulse with respect to a secondframe of digital data with a second marker; wherein the radio system isfurther configured to propagate the second Gaussian pulse in the radiosystem to the antenna, the radio system configured to convert the seconddigital representation of the second Gaussian pulse to a second radiofrequency signal transmitted at the antenna; wherein the spectrumanalyzer is configured to measure when the second Gaussian pulse occursin the second radio frequency signal based on the second marker; andwherein the radio system is further configured to determine a downlinkpropagation delay for the radio system between application of the seconddigital representation of the second Gaussian pulse at the digitalinterface and transmission of the second radio frequency signal at theantenna.

Example 53 includes the system of Example 52, further comprising:wherein the radio system is further configured to determine an uplinkpropagation delay for the radio system by subtracting the downlinkpropagation delay for the radio system from the round trip propagationdelay for the radio system.

Example 54 includes the system of Example 53, wherein the uplinkpropagation delay includes intrinsic delay and transmission delay acrossa communication medium between two components of the radio system.

Example 55 includes the system of any of Examples 53-54, wherein theuplink propagation delay includes a first uplink intrinsic delay withinan antenna unit communicatively coupled to the antenna and remotelycoupled with the digital interface across a communication medium;wherein the uplink propagation delay further includes a second uplinkintrinsic delay within the digital interface to the radio system; andwherein the uplink propagation delay further includes a transmissiondelay across the communication medium between the antenna unit and thedigital interface.

Example 56 includes the system of Example 55, further comprising:wherein the radio system is further configured to measure the digitaluplink transmission delay across the communication medium between theantenna unit and the digital interface; and wherein the radio system isfurther configured to subtract the digital uplink transmission delayfrom the uplink propagation delay to determine a total uplink intrinsicdelay including the first uplink intrinsic delay and the second uplinkintrinsic delay.

Example 57 includes the system of any of Examples 51-56, wherein thefirst waveform generator is further configured to provide the firstmarker to the spectrum analyzer to determine when the first Gaussianpulse occurs.

Example 58 includes the system of any of Examples 51-57, wherein thedigital interface is part of a host unit; wherein the antenna is part ofan antenna unit remote to the host unit; and wherein the host unit andthe antenna unit are communicatively coupled via a wired communicationmedium.

Example 59 includes the system of Example 58, wherein the wiredcommunication medium is at least one of an optical fiber, coaxial cable,and twisted pair.

What is claimed is:
 1. A method for measuring downlink delay in a radiosystem, comprising: applying a digital representation of a pulse to adigital interface of the radio system; marking the digitalrepresentation of the pulse with respect to a frame of digital data witha marker; propagating the pulse in the radio system to an antenna, theradio system configured to convert the digital representation of thepulse to a radio frequency signal transmitted at the antenna; measuringwhen the pulse occurs in the radio frequency signal based on the marker;and determining a downlink propagation delay for the radio systembetween application of the digital representation of the pulse at thedigital interface and transmission of the radio frequency signal at theantenna.
 2. The method of claim 1, wherein the downlink propagationdelay includes intrinsic delay and transmission delay across acommunication medium between two components of the radio system.
 3. Themethod of claim 1, wherein the downlink propagation delay includes afirst intrinsic delay within the digital interface to the radio system;wherein the downlink propagation delay includes a second intrinsic delaywithin an antenna unit communicatively coupled to the antenna andremotely coupled with the digital interface across a communicationmedium; and wherein the downlink propagation delay further includes atransmission delay across the communication medium between the digitalinterface and the antenna unit.
 4. The method of claim 3, furthercomprising: measuring the transmission delay across the communicationmedium between the digital interface and the antenna unit; andsubtracting the transmission delay from the downlink propagation delayto determine a total intrinsic delay including the first intrinsic delayand the second intrinsic delay.
 5. The method of claim 1, furthercomprising: generating the pulse; and converting the pulse to a digitalrepresentation of the pulse.
 6. The method of claim 1, wherein measuringwhen the pulse occurs in the radio frequency signal based on the markeroccurs using a spectrum analyzer.
 7. The method of claim 1, furthercomprising providing the marker from a first device used to generate thedigital representation of the pulse to a second device used to analyzethe radio frequency signal to determine when the pulse occurs.
 8. Themethod of claim 1, wherein propagating the pulse in the radio system tothe antenna occurs across a wired communication medium.
 9. The method ofclaim 8, wherein the wired communication medium is at least one of anoptical fiber, coaxial cable, and twisted pair.
 10. The method of claim1, wherein propagating the pulse in the radio system to the antennaoccurs across a wireless link.
 11. The method of claim 1, wherein thepulse provides minimal distortion in bandwidth limited radio frequencychannels.
 12. A system for measuring downlink delay in a radio system,comprising: a waveform generator configured to generate a digitalrepresentation of a pulse and apply it to a digital interface of theradio system; wherein the waveform generator is further configured tomark the digital representation of the pulse with respect to a frame ofdigital data with a marker; wherein the radio system is configured topropagate the pulse and convert the digital representation of the pulseto a radio frequency signal transmitted at an antenna; a spectrumanalyzer configured to measure when the pulse occurs in the radiofrequency signal based on the marker; and wherein the system isconfigured to determine a downlink propagation delay for the radiosystem between application of the digital representation of the pulse atthe digital interface and transmission of the radio frequency signal atthe antenna.
 13. The system of claim 12, wherein the downlinkpropagation delay includes intrinsic delay and transmission delay acrossa communication medium between two components of the radio system. 14.The system of claim 12, wherein the downlink propagation delay includesa first intrinsic delay within the digital interface to the radiosystem; wherein the downlink propagation delay includes a secondintrinsic delay within an antenna unit communicatively coupled to theantenna and remotely coupled with the digital interface across acommunication medium; and wherein the downlink propagation delay furtherincludes a transmission delay across the communication medium betweenthe digital interface and the antenna unit.
 15. The system of claim 14,further comprising: wherein the system is further configured todetermine the transmission delay across the communication medium betweenthe digital interface and the antenna unit; and wherein the system isfurther configured to subtract the transmission delay from the downlinkpropagation delay to determine a total intrinsic delay including thefirst intrinsic delay and the second intrinsic delay.
 16. The system ofclaim 12, wherein the waveform generator is configured to provide themarker to the spectrum analyzer via a communication medium separate fromthe radio system.
 17. The system of claim 12, wherein the radio systemincludes a digital host having the digital interface; wherein the radiosystem includes an antenna unit having the antenna; wherein the digitalhost is communicatively coupled to the antenna unit via a communicationmedium; wherein the digital host is configured to communicate the pulseto the antenna unit via the communication medium; and wherein theantenna unit is configured to convert the digital representation of thepulse to a radio frequency signal transmitted at the antenna.
 18. Thesystem of claim 12, wherein the radio system includes a wiredcommunication medium, wherein the radio system is configured topropagate the pulse across the wired communication medium.
 19. Thesystem of claim 18, wherein the wired communication medium is at leastone of an optical fiber, coaxial cable, and twisted pair.
 20. The systemof claim 12, wherein the radio system is configured to propagate thepulse across a wireless link within the radio system.
 21. The system ofclaim 12, wherein the pulse provides minimal distortion in bandwidthlimited radio frequency channels.
 22. A method for measuring uplinkdelay in a radio system, comprising: applying a pulse to a radiofrequency signal input at an antenna; marking the pulse with respect toa frame of digital data with a marker; propagating the pulse in theradio system to a digital interface of the radio system, the radiosystem configured to convert the pulse to a digital representation ofthe pulse communicated at the digital interface in a digital signal;measuring when the pulse occurs in the digital signal based on themarker; and determining an uplink propagation delay for the radio systembetween application of the pulse to the radio frequency signal input atthe antenna and communication of the digital representation of the pulseat the digital interface in the digital signal.
 23. The method of claim22, wherein the uplink propagation delay includes intrinsic delay andtransmission delay across a communication medium between two componentsof the radio system.
 24. The method of claim 22, wherein the uplinkpropagation delay includes a first intrinsic delay within an antennaunit communicatively coupled to the antenna and remotely coupled withthe digital interface across a communication medium; wherein the uplinkpropagation delay further includes a second intrinsic delay within thedigital interface to the radio system; and wherein the uplinkpropagation delay further includes a transmission delay across thecommunication medium between the antenna unit and the digital interface.25. The method of claim 24, further comprising: measuring the digitaltransmission delay across the communication medium between the antennaunit and the digital interface; and subtracting the digital transmissiondelay from the uplink propagation delay to determine a total intrinsicdelay including the first intrinsic delay and the second intrinsicdelay.
 26. The method of claim 22, further comprising: generating thepulse; and converting the digital representation of the pulse back tothe pulse.
 27. The method of claim 22, wherein measuring when the pulseoccurs in the digital signal based on the marker occurs using a spectrumanalyzer.
 28. The method of claim 22, further comprising providing themarker from a first device used to generate the pulse to a second deviceused to analyze the digital signal to determine when the pulse occurs.29. The method of claim 22, wherein propagating the pulse in the radiosystem to the digital interface occurs across a wired communicationmedium.
 30. The method of claim 29, wherein the wired communicationmedium is at least one of an optical fiber, coaxial cable, and twistedpair.
 31. The method of claim 22, wherein propagating the pulse in theradio system to the digital interface occurs across a wireless link. 32.The method of claim 22, wherein the pulse provides minimal distortion inbandwidth limited radio frequency channels.
 33. A system for measuringuplink delay in a radio system, comprising: a waveform generatorconfigured to generate a pulse and apply it to an antenna of the radiosystem; wherein the waveform generator is further configured to mark thepulse with respect to a frame of digital data with a marker; wherein theradio system is configured to propagate the pulse and convert the pulseto a digital representation of the pulse output at a digital interfaceof the radio system; a spectrum analyzer configured to measure when thedigital representation of the pulse occurs in a digital signal outputfrom the digital interface of the radio system; and wherein the systemis configured to determine an uplink propagation delay for the radiosystem between application of the pulse at the antenna of the radiosystem and output of the digital signal at the digital interface of theradio system.
 34. The system of claim 33, wherein the uplink propagationdelay includes intrinsic delay and transmission delay across acommunication medium between two components of the radio system.
 35. Thesystem of claim 33, wherein the uplink propagation delay includes afirst intrinsic delay within the digital interface to the radio system;wherein the uplink propagation delay includes a second intrinsic delaywithin an antenna unit communicatively coupled to the antenna andremotely coupled with the digital interface across a communicationmedium; and wherein the uplink propagation delay further includes atransmission delay across the communication medium between the digitalinterface and the antenna unit.
 36. The system of claim 35, furthercomprising: wherein the system is further configured to determine theuplink transmission delay across the communication medium between thedigital interface and the antenna unit; and wherein the system isfurther configured to subtract the uplink transmission delay from theuplink propagation delay to determine a total intrinsic delay includingthe first intrinsic delay and the second intrinsic delay.
 37. The systemof claim 33, wherein the waveform generator is configured to provide themarker to the spectrum analyzer via a communication medium separate fromthe radio system.
 38. The system of claim 33, wherein the radio systemincludes a digital host having the digital interface; wherein the radiosystem includes an antenna unit having the antenna; wherein the digitalhost is communicatively coupled to the antenna unit via a communicationmedium; wherein the antenna unit is configured to communicate thedigital pulse to the digital host via the communication medium; andwherein the antenna unit is configured to convert a radio frequencysignal received at the antenna and including the pulse to a digitalrepresentation of the pulse output at the digital interface.
 39. Thesystem of claim 33, wherein the radio system includes a wiredcommunication medium, wherein the radio system is configured topropagate the pulse across the wired communication medium.
 40. Thesystem of claim 39, wherein the wired communication medium is at leastone of an optical fiber, coaxial cable, and twisted pair.
 41. The systemof claim 33, wherein the radio system is configured to propagate thepulse across a wireless link within the radio system.
 42. The system ofclaim 33, wherein the pulse provides minimal distortion in bandwidthlimited radio frequency channels.
 43. A method for measuring delay in aradio system, comprising: applying a first pulse to a radio frequencysignal input at an antenna; marking the first pulse with respect to afirst frame of digital data with a first marker; propagating the firstpulse in the radio system to a digital interface of the radio system,the radio system configured to convert the first pulse to a firstdigital representation of the first pulse communicated at the digitalinterface in a first digital signal; looping back the first pulse in theradio system from the digital interface of the radio system to a radiofrequency signal output at the antenna, the radio system configured toconvert the first digital representation of the first pulse to a firstradio frequency signal having the first pulse transmitted at theantenna; measuring when the first pulse occurs in the first radiofrequency signal based on the first marker; and determining a round trippropagation delay for the radio system between application of the firstpulse to the radio frequency signal input at the antenna andcommunication of the first radio frequency signal having the first pulsetransmitted at the radio frequency signal output at the antenna.
 44. Themethod of claim 43, further comprising: applying a second digitalrepresentation of a second pulse to the digital interface of the radiosystem; marking the second digital representation of the second pulsewith respect to a second frame of digital data with a second marker;propagating the second pulse in the radio system to the antenna, theradio system configured to convert the second digital representation ofthe second pulse to a second radio frequency signal transmitted at theantenna; measuring when the second pulse occurs in the second radiofrequency signal based on the second marker; and determining a downlinkpropagation delay for the radio system between application of the seconddigital representation of the second pulse at the digital interface andtransmission of the second radio frequency signal at the antenna. 45.The method of claim 44, further comprising: determining an uplinkpropagation delay for the radio system by subtracting the downlinkpropagation delay for the radio system from the round trip propagationdelay for the radio system.
 46. The method of claim 45, wherein at leastone of the downlink propagation delay and the uplink propagation delayincludes intrinsic delay and transmission delay across a communicationmedium between two components of the radio system.
 47. The method ofclaim 45, wherein at least one of the downlink propagation delay and theuplink propagation delay includes: a first intrinsic delay within anantenna unit communicatively coupled to the antenna and remotely coupledwith the digital interface across a communication medium; a secondintrinsic delay within the digital interface to the radio system; and atransmission delay across the communication medium between the antennaunit and the digital interface.
 48. The method of claim 48, furthercomprising for at least one of the downlink propagation delay and theuplink propagation delay: measuring the digital transmission delayacross the communication medium between the antenna unit and the digitalinterface; and subtracting the digital transmission delay from theuplink propagation delay to determine a total intrinsic delay includingthe first intrinsic delay and the second intrinsic delay.
 49. The methodof claim 43, further comprising: generating the first pulse.
 50. Themethod of claim 43, wherein measuring when the pulse occurs in thedigital signal based on the marker occurs using a spectrum analyzer. 51.The method of claim 43, further comprising providing the first markerfrom a first device used to generate the first pulse to a second deviceused to analyze the first radio frequency signal to determine when thefirst pulse occurs.
 52. The method of claim 43, wherein propagating thepulse in the radio system to the digital interface occurs across a wiredcommunication medium.
 53. The method of claim 52, wherein the wiredcommunication medium is at least one of an optical fiber, coaxial cable,and twisted pair.
 54. The method of claim 43, wherein propagating thepulse in the radio system to the digital interface occurs across awireless link.
 55. The method of claim 43, wherein the pulse providesminimal distortion in bandwidth limited radio frequency channels.
 56. Asystem for measuring delay in a radio system, comprising: a firstwaveform generator configured to generate a first pulse and to apply thefirst pulse to an antenna of the radio system; wherein the firstwaveform generator is further configured to mark the first pulse withrespect to a first frame of digital data with a first marker; whereinthe radio system is configured to propagate the first pulse and convertthe first pulse to a first digital representation of the first pulseoutput at a digital interface of the radio system; wherein the radiosystem is further configured to loop back the first pulse in the radiosystem from the digital interface of the radio system to a radiofrequency signal output at the antenna and to convert the first digitalrepresentation of the first pulse to a first radio frequency signalhaving the first pulse transmitted at the antenna; a spectrum analyzerconfigured to measure when the first pulse occurs in the first radiofrequency signal output at the antenna based on the first marker;wherein the system is configured to determine a round trip propagationdelay for the radio system between application of the first pulse to theradio frequency signal input at the antenna and communication of thefirst radio frequency signal having the first pulse transmitted at theradio frequency signal output at the antenna.
 57. The system of claim56, further comprising: a second digital waveform generator configuredto generate a second digital representation of a second pulse and toapply the second digital representation of the second pulse to thedigital interface of the radio system; wherein the second waveformgenerator is further configured to mark the second digitalrepresentation of the second pulse with respect to a second frame ofdigital data with a second marker; wherein the radio system is furtherconfigured to propagate the second pulse in the radio system to theantenna, the radio system configured to convert the second digitalrepresentation of the second pulse to a second radio frequency signaltransmitted at the antenna; wherein the spectrum analyzer is configuredto measure when the second pulse occurs in the second radio frequencysignal based on the second marker; and wherein the radio system isfurther configured to determine a downlink propagation delay for theradio system between application of the second digital representation ofthe second pulse at the digital interface and transmission of the secondradio frequency signal at the antenna.
 58. The system of claim 57,further comprising: wherein the radio system is further configured todetermine an uplink propagation delay for the radio system bysubtracting the downlink propagation delay for the radio system from theround trip propagation delay for the radio system.
 59. The system ofclaim 58, wherein at least one of the downlink propagation delay and theuplink propagation delay includes intrinsic delay and transmission delayacross a communication medium between two components of the radiosystem.
 60. The system of claim 58, wherein at least one of the downlinkpropagation delay and the uplink propagation delay includes: a firstuplink intrinsic delay within an antenna unit communicatively coupled tothe antenna and remotely coupled with the digital interface across acommunication medium; a second uplink intrinsic delay within the digitalinterface to the radio system; and a transmission delay across thecommunication medium between the antenna unit and the digital interface.61. The system of claim 60, further comprising for at least one of thedownlink propagation delay and the uplink propagation delay: wherein theradio system is further configured to measure the digital uplinktransmission delay across the communication medium between the antennaunit and the digital interface; and wherein the radio system is furtherconfigured to subtract the digital uplink transmission delay from theuplink propagation delay to determine a total uplink intrinsic delayincluding the first uplink intrinsic delay and the second uplinkintrinsic delay.
 62. The system of claim 56, wherein the first waveformgenerator is further configured to provide the first marker to thespectrum analyzer to determine when the first pulse occurs.
 63. Thesystem of claim 56, wherein the digital interface is part of a hostunit; wherein the antenna is part of an antenna unit remote to the hostunit; and wherein the host unit and the antenna unit are communicativelycoupled via a wired communication medium.
 64. The system of claim 56,wherein the radio system includes a wired communication medium, whereinthe radio system is configured to propagate the pulse across the wiredcommunication medium.
 65. The system of claim 64, wherein the wiredcommunication medium is at least one of an optical fiber, coaxial cable,and twisted pair.
 66. The system of claim 56, wherein the radio systemis configured to propagate the pulse across a wireless link within theradio system.
 67. The system of claim 56, wherein the pulse providesminimal distortion in bandwidth limited radio frequency channels.